


Achieving the Hadamard Product

by GoddessofBirth



Series: Factoring Out Binomials [3]
Category: Teen Wolf (TV)
Genre: And thinks he still has what he wants, Blow Jobs, Derek is still a creeper, I REGRET NOTHING, Isaac can't have what he wants, Jealousy, M/M, Marking, One sided Derek/Stiles, Smut, Stiles and Isaac are a fucked up mess, Stiles has a love affair with Planned Parenthood, Stiles has learned how to lie to werewolves, Stiles is oblivious, Things are unraveling faster now, Trouble is brewing
Language: English
Status: Completed
Published: 2012-07-10
Updated: 2012-07-15
Packaged: 2017-11-09 13:57:53
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 7,027
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/456246
Author URL: https://archiveofourown.org/users/GoddessofBirth/pseuds/GoddessofBirth
Summary: <blockquote class="userstuff">
              <p>There's a katsune on the loose in Beacon Hills, forcing the two packs to work together.  Frankly, Stiles is more worried about surviving Chemistry class and his meeting with Derek.  And then there's this thing that happens in the locker room.</p>
            </blockquote>





	1. Matrices

**Author's Note:**

> Just as an aside, this goes canon AU from episode 2 x 06. I'll probably incorporate elements from the remaining episodes, but I'm not going to be held to them.

Free condoms, it turns out, are easily attained from Planned Parenthood. You can actually just walk in and grab them out of a fishbowl, no questions. Of course, Stiles feels too guilty to do that, so he instead makes an appointment and lets them test him for every STD imaginable – even though, yeah, not much of a chance of any of those coming back positive – and even pays out a whole two weeks gas money, since he _can_ , because that means one more person who _can't,_ can still get help. 

 

(And okay, maybe Stiles spends an inordinate amount of time on their website reading all about their mission, and maybe he's fallen just a little bit in love with them, and maybe, just maybe, he makes an anonymous donation, but whatever, he's not telling anybody that.)

 

And when they get to the point in the health interview where they ask him if he has sex with males, females, or both, he turns a brilliant shade of red, but balls up and says boys, because even though he actually _hasn't_ , that's what he's obviously planning on, so may as well get that out there. The RN doesn't react at all, just moves to the next question on the list and then asks Stiles if he has any questions of his own. He does, oh how he _does_ , but he's not quite bold enough to ask them, so instead he's given a handful of pamphlets, and a smile, and walks out the door with what he came for, as well as feeling like he's now entitled to sneak in from time to time and snag those condoms, guilt free.

 

Of course, it's a totally moot point, because the three original ones he carries out with him are still sitting, all snug and unused in their shiny wrappers, stuffed deep, deep in the back of his underwear drawer. 

 

Because they haven't done it. 

 

Sex, that is.

 

Yes, there's been copious making out in the month or so since he punches Isaac in the face and it turns into humping each other against an oak tree, and yes, they've finally rounded second base and hit third. But they never take more than shirts off, never grope underneath pants and boxers, never actually get naked when they're frantically rocking into each other and breathing each others air. Isaac always has a change of clothes now, always showers, always stuffs his dirty shirt underneath Stiles' pillow before he leaves.

 

There are orgasms a plenty. But no sex.

 

Stiles is pretty sure it's because they both know if they cross that line, they're going to have to do something about it. You can't actually sleep with your enemy and pretend it's not happening, right? At least Stiles doesn't think he could do it. He's not sure about Isaac, but then again, there's very little about Isaac that he  _is_ sure of. Like the whole enemy thing. Are they enemies? Do you lay your head in your enemy's lap? Do you read out loud, until you're hoarse, to someone you might one day have to kill? Do you do everything you can to wring that one certain sound out of someone you'll stab if you get the order? It's not hate(almost)sex, it's never been hate(almost)sex, not from the very first time, but he doesn't know what it is. And he's ninety-nine percent sure Isaac doesn't know what it is, either, is pretty sure Isaac is almost always just as confused as he is.

 

It's the only thing that keeps him from driving himself crazy.

 

They're sitting in chemistry, and Isaac is trying to balance a pencil on it's tip, while mocking Scott's latest attempts to get the Argents to accept him.

 

“He should have gotten rid of her when he had the chance. I would have.”

 

“Yeah, sure,” Stiles says absently, jotting down the results of their last experiment. “I'm sure that would have worked out just as well as when you decided to kill Lydia. Did I ever mention your pack kind of sucks?”

 

“Did I ever mention how easily I kicked your ass that night? Because it was pretty easy.”

 

“But – ” Stiles straightens up and stretches, “-- not as easily as Scott kicked yours.”

 

He scratches lazily at the center of his chest, a move that looks casual to any onlookers – and they have many – but which invariably draws Isaac's eyes. Stiles grins evilly and continues to rub his fingers over the place where his t-shirt covers the mark he's carried since that first night. Every time it threatens to fade, Isaac just puts it back, sucks it red and deep while his palm rocks against Stiles' zipper.

 

Isaac leans in close and bares his teeth, runs his tongue over distended fangs. “ _Stop_ ,” he hisses, then plucks their paper from Stiles and starts erasing his calculations.

 

Chemistry class is like trying to navigate barefoot through broken glass, because it's the one class that every supernatural teenager somehow manages to have together. Seriously, it's a walking, talking brochure of things that go bump in the night, and preternatural hearing means any conversation may as well be broadcast over a loudspeaker. Isaac's oh so clever maneuver has come back to bite them both in the ass.

 

Normally, they manage business as usual just fine, but every once in awhile, one of them likes to push, and he's never exactly sure what sets them off. It's like an itch, under his skin, the need to make Isaac blush, or jerk, or make some excuse to press in a little too tight against him. It's one of the few times he's glad Scott is so obsessed with Allison, otherwise he knows Stiles too well not to figure out something's going on.

 

Isaac hands the paper back to him, and he checks over his corrections. Isaac is a lot more detail oriented than he is, while Stiles is better at putting the pieces together to solve the puzzle. He's pretty sure that if Mr. Harris didn't hate him so much, they'd be his star pupils.

 

“Got big plans for your night off of creepering? Gonna go howl at the moon? Chase some rabbits?” His dad starts a three day weekend tonight, which nominally means no little werewolves taking up space in his yard. Scott lets out a bark of laughter before he gets it under control and just shrugs when Mr. Harris narrows his eyes at him. He gives Stiles a covert thumbs up.

 

Isaac hooks his ankle around Stiles' for a second, for just a second, and then starts setting up materials for their next run through. “While you're being useless, we'll be catching the kitsune.”

 

“I'm sure Derek has every confidence in you three's ability to hunt and slaughter. Which is why he's making a special visit to his numero uno source of information. Some days I'm pretty sure I'm the only useful person between these two packs.”

 

Isaac jerks beside him, almost dropping the beaker. “What?”

 

Stiles has been so caught up in the familiar rhythm of their banter that he's caught completely off guard at the look of panic on Isaac's face.

 

“Uh, yeah. Crawling through the window and everything tonight, just like old times. He and Scott decided there's been too many deaths for us to be working this separately. And well, no offense, but your research department sucks. You'd think Derek would have planned ahead, bitten a librarian or something. Did he seriously not tell you guys any of this? Do you guys not have, like, planning sessions and stuff? No wonder we always win.”

 

Isaac shoves the paper between them, then bends down low over it, pencil in hand. Stiles follows suit, pulling the open text book over as well, until they look for all the world like they're knee deep in calculations.

 

“Don't tell him.” Isaac's voice is well below a whisper, barely vocalized at all, but Stiles has had a lot of practice in this, and he watches his lips to make sure he gets it all.

 

He answers just as low. “No, really? And here I was thinking about sharing all my plans to deflower his little baby pup. Jesus, give me some credit.”

 

Isaac's eyebrow quirks, and a little bit of the fear leeches from his face. Good. Stiles hates that look on him. “So that's the plan? And here I was thinking it was the other way around.”

 

There are so many things Stiles could say to that,  _wants_ to say to that, but they're out of their allotted time, so he settles for a breezy “Six of one, half dozen of the other,” and sits back up before he can think too hard about the fact they've more or less just put their cards on the table.

 

They finish the experiment – nothing requiring eating crystals formed in half cleaned beakers this time, thank god – with ten minutes to spare, but Isaac is acting  _strange._ He's touched Stiles no less than five times in the last thirty seconds; casual touches: a hand on his shoulder, his leg pressing against Stiles, fingers on his arm. Once he actually leans over Stiles to grab the notebook and pushes his palm against his chest, unerringly finding his mark. From the corner of his eye, Stiles sees Allison frowning, tugging on Scott's sleeve.

 

“Dude! What are you doing?” he hisses, Isaac's hand just inches from his knee. “Handsy much?” Isaac freezes and stares at his hand, blinks rapidly and then shoves his chair away from Stiles so fast it makes the screeching sound of a dying cat. Stiles looks over his shoulder at Scott and shrugs helplessly at the same time Isaac shrugs at Erica's questioning look.

 

Oh, god, they really, really suck at this.

 

Luckily, Erica and Scott suck even more, or at least he and Isaac have been careful enough that the moment is dismissed as just one of those freaky things Isaac does to annoy Stiles. Isaac hastily scrawls on a piece of paper and passes it to him.

 

_Sorry. I didn't know._

 

Stiles turns his head enough so that Isaac can see his face, makes an open palmed “what can you do” gesture, and twists his mouth up in a one sided grin.

 

They don't interact for the rest of the class.

 

* * * * * * 

 

That Stiles has after school detention is so run of the mill that it doesn't deserve special mention. That it makes him late for lacrosse practice is also old hat. The fact that Coach Finstock is in an especially foul mood would also be nothing to take note of, except that in this instance he decides to take it out on Stiles and his tardiness, and makes him run suicide after suicide once practice is over, until there's no one on the team left, and Stiles' insides hurt so much that he pukes on the side of the field.

 

“ _Stilinski! Hit the showers and get out of here! You're making me late for my date!”_ Coach Finstock always talks in either italics or caps lock, and Stiles refrains from telling him he would already be long gone if wasn't for Coach. A part of him is tempted to just skip the shower and drive home, fling himself in bed and get a nap before he has to deal with Derek freaking Hale and his mood swings, but he's sweated enough that his uniform really, really needs to hit the school laundry bin, and once he's stripped down, he may as well go the whole shebang.

 

The locker room is predictably deserted. He hears Coach muttering to himself before he yells at Stiles to lock up on his way out and not to break anything, and then the slamming of the outer door as he leaves. The only reason Stiles even bothers to turn the lights back on is that the number of times a werewolf or werelizard has tried to kill him in a darkened school room has maybe left him kind of scarred.

 

He whistles a little as he flips the water on and cranks the heat up to high. His freaking legs are already killing him – he's in shape, but suicides exist for no other reason than to destroy you – and he braces his arms against the tile and bows his head, letting the steam and spray work out some of the kinks. He stands there for way too long before finally turning to grab the soap.

 

Isaac is standing just beyond the reach of the shower, chewing on his thumbnail and watching him intently.

 

“Holy mother of fuck! What the - ! Goddammit, Isaac, you're gonna give me a freakin' heart attack!” As Stiles' heart slows back to a more healthy speed, he remembers the little fact that he's butt ass naked.

 

“Um...what are you doing here? Figured you'd be off stalking the local supernatural life.” This is no big deal, he's cool, he's fine. He's not five seconds away from freaking the fuck out.

 

“I wanted to see you.” And Jesus Christ is Isaac seeing him. He's not even being subtle about the way his eyes are roaming over his body. Sometimes Isaac is as skittish and shy as a vestal virgin. This is not one of those times. Unfortunately, it _is_ one of those times for him.

 

“So.” Stiles crosses his arms and tucks his hands into his arm pits, spitting water out as it continues to drip into his mouth. He's not going to cower and cover up like a little girl. He's a man, dammit, or at least a semi-respectable high school athlete. Locker room nudity should be old hat. “Here we are. Me naked. You...not.”

 

Isaac takes a step forward and reaches for the hem of his shirt, the fine spray from the shower already dotting the fabric. “I'll fix it.”

 

Stiles bangs his head back against the tile in frustration. It's one of the little things he's learned about Isaac in the last month or so that they've been doing this...whatever. No matter what front he puts up, there's a part of him that's eager to please, that is desperate not to disappoint. It's usually outweighed by the asshole werewolf part of him, but it's definitely there. Stiles has learned to word things very carefully at those times.

 

“It wasn't a complaint. Just a...you know...observation of the fact I'm butt ass naked while you're a fully clothed creeper.”

 

Isaac has shed his shirt and kicked off his shoes at this point, and is starting to shimmy his pants down, underwear and all, throwing everything behind him out onto dry ground. He gives Stiles a funny look. “I know.”

 

“So, what? You just thought it would be a good idea for us both to get naked together – for the first time, I might add – in a semi-public locker room in a very public school?”

 

Isaac grins, slow and easy and completely feral as he steps out of his pants and takes two more steps toward Stiles, until droplets of water start beading on his eyelashes and running down his shoulders.

 

“Yes.” He's barely a hands breadth away now, and Stiles is having a very, very hard time keeping his eyes _up._

 

“Where anybody could walk in at any time? Really?”

 

“I'll hear them first. And school was over hours ago. I wanted to see you.” He takes the last remaining step, and then they're skin against skin, wet, _wet_ skin against skin, and he should turn the water off because he can barely see, but his brain has decided it's definitely time to cease higher order functions.

 

“Okay, yeah, this is one of your better ideas,” he gasps, because holy mother of fuck, that's a lot of skin, and Isaac's dick is definitely saying hello to his. He kisses Isaac, wet and open, because that's another thing he's learned about him – nothing shuts Isaac's brain down faster than tonguing into his mouth, both throttles open and no holding back.

 

There's a lot of touching between one minute and the next, a lot of hands using water as an excuse to slide recklessly from one place to the other. Isaac is strangely intent, even more so than usual, letting his lips cut direct paths from Stiles' ear to his breastbone, over and over again. He makes an angry, distressed noise when Stiles pushes him back a few inches.

 

“No...no,” Stiles says breathlessly. “I just...I just want to look for a second.” Dammit, he wants to _see_ what nakedness looks like, outside of his own and outside of porn stars that don't count as anything close to real. He has one hand on Isaac's hip and the other wrapped around his neck, and he can feel Isaac's pulse underneath his thumb, rabbit quick. Isaac stills, a crease between his eyebrows as he watches Stiles look at him; Stiles gets the feeling he's right on the edge of running, although he doesn't know why.

 

And _Jesus_ , he hates to use the word beautiful, but fuck, that's what Isaac is. Scott, and Derek and Boyd, for that matter, are like brick walls, muscle and bulk that could give a battering ram a run for its money. Isaac, though, is all long, lean muscles and lines, dips and hollows and precise angles. The other male werewolves look like they should be what they are, but Isaac should be some kind of dark angel, the kind that makes you kneel at their feet even as they kill you.

 

He can't even blush as he finally lets his looking drift south. He's that far gone, and a part of his brain screams that this is _bad, bad, bad_ that he wants Isaac on so many other levels than physical. He's too young, and they're too fucked up, and more than anything, they aren't Scott and Allison, could never _be_ Scott and Allison, in all their glorious and adorable stupidity. It's not the first time he's had the thought, and luckily, it's even easier to smother when put up against the sight of a naked Isaac.

 

Water has gathered in Isaac's pubic thatch, and Jesus Christ he's hard, just as hard as Stiles, foreskin pulled back and taunt, head swollen and almost purple. Stiles has always let his curiosity lead, and this is no different, even if the curiosity is overlain with his mouth going dry and his balls pulling tight. He brushes his palm over Isaac's tip, wet and sticky with more than just water, curls his hand down and around.

 

Isaac whines, the sound pained and desperate. Stiles yanks his stare away from where he's been mesmerized by the sight of Isaac's dick in his hand, to see that Isaac's head is tipped back, mouth hanging open and eyes squeezed shut.

 

“God,” Stiles breathes. “You're gorgeous.”

 

Isaac's head snaps down and his eyes fly open, and Stiles _does_ blush then, because who says that to another guy? It doesn't seem to bother Isaac; he moves with sudden determination, crowding Stiles against the wall and a little to the side, so that they're out of the direct spray of the shower head. Stiles' hand is still trapped between them, so when Isaac slams their hips together, his palm slides down Isaac's shaft, while his knuckles catch along the length of his. He hisses, bites his lip, and Isaac laughs, out of control and sharp, and then abruptly drops to his knees.

 

“What are you...are you seriously...oh my God, you are – _nnggg_.” Stiles stuffs his fist into his mouth to keep from screaming when Isaac grabs his hips and just fucking _goes_ for it, wraps his mouth around Stiles' dick and takes him in as far as he can, far enough that Stiles can feel the flutter of throat muscles around his tip.

 

And oh fuck, oh fuck, oh fuck, it's sloppy and wet and not perfect and absolutely the best freaking thing he's ever felt. His head cracks back against the tile again.

 

“Oh my _God_.” And he can't remember blow job etiquette. Hands in hair? Rude? Not Rude? Touch? Don't Touch? Isaac is kind of pinning his hips to the wall, so the matter of actually fucking his mouth isn't one of the things he has to consider. But the hair...he really needs to know about the hair.

 

In the end, Isaac more or less makes the choice for him, when he looks up and grins around Stiles' cock, and lets his eyes go yellow. And the bastard is doing it on purpose, Stiles has no doubt about that – Stiles isn't the only person to have figured out someone's kinky little quirks. He shudders and babbles and his hands automatically shoot out and tunnel into Isaac's curls, wrap them around his fingers and grip tight. Isaac's eyes roll back in his head and he does his own bit of shuddering before he recovers, locks his eyes with Stiles' and sucks him back down.

 

Stiles can't look away, can't stop watching his dick move in and out of the round “o” of Isaac's mouth, the shiny slick of spit easily discernible from the water dripping off them, can't not stare at the way Isaac's pupils blow wide as he works him, making his irises burn even brighter in contrast. Then he tongues into Stiles' slit, and Stiles yanks at his hair, trying to warn him, get him to move.

 

“Isaac..Isaac...I'm gonna...gonna...” But Isaac refuses to be moved, shoves Stiles' hips harder into the wall, presses his face into his pelvis, and Stiles comes, his whole body jerking almost painfully and his vision whiting out. Somewhere in the distance he can hear Isaac gagging, but still not drawing back, not until Stiles is limp and rung out and only held up by Isaac's hands. Then he turns his face into Stiles' thigh, whispers something Stiles can't quite hear, and then lets go, sliding back on his haunches. His face is tight, strained – Stiles may have come, but Isaac didn't, and his entire body is practically begging for it.

 

Without the support, Stiles collapses to his ass on the tiles. “Oh God...oh God,” he pants, and then he's scrambling across the floor, climbing on top of Isaac until he's straddling him. He grabs his dick in one hand and starts jerking him off furiously while he uses the other to yank his head back by his hair until he's bowed back underneath Stiles, forced to carry all his weight on his arms.

 

“Come on, come on,” Stiles gasps into his ear. “Give it, give it, give it. _Isaac, give it._ ”

 

And then Isaac convulses under him, cum painting both of their chests, which should totally be gross, but totally isn't. Stiles catches Isaac before he can fall back onto the floor, holding him in an unintentional embrace as their breath mixes between them, sounding like hyperventilation, sounding like panic, sounding like they've just gotten off harder than either of them have ever gotten off in their admittedly short lives.

 

“Oh, God,” Stiles finally groans. “We're probably gonna get some freaky ass fungus now. Locker room shower? Not exactly sanitary.” It's not really what he wants to say, maybe not what he means to say, but it's what his mouth chooses to focus on at the moment.

 

Isaac just stares at him, his expression shell shocked and bewildered, his lips cherry red and swollen, because _fuck,_ he'd had Stiles' dick sliding in between them, and there's cum – _Stiles' cum_ – dripping from one corner of his mouth. What does he do? What is he supposed to do? There's no handbook for this, none of the movies he's seen or the porn he's watched have told him how to handle this kind of after, how he's supposed to handle all the millions of thoughts chasing through his brain and the feelings swimming around in his chest.

 

He doesn't know, he doesn't know -

 

He leans forward and sucks at the corner of Isaac's mouth, licks himself off Isaac's face, and feels Isaac reaching between them and running his fingers through the mess on his chest. He's practically pushing it into Stiles' skin...no, he _is_ pushing it into Stiles' skin, and he's pretty sure this is something related to the same thing his stealth move with Stiles' shirt was related to, only he's not sure what and he hasn't figured out how to ask Scott about it.

 

The water is finally running cold when Isaac is satisfied, and then Stiles pulls him to his feet and lets him painstakingly wash it carefully and thoroughly away. When they're both squeaky clean, all the evidence washed down the drain, Isaac leans in and bites Stiles' bottom lip.

 

“Don't tell him,” he whispers again, and then swipes his thumb across the bar of soap and rubs it over Stiles' mouth. Then he grins, that cocky half smirk that always has Stiles' fist itching to connect to his jaw, and backs out of the shower, grabbing his clothes as he goes.

 

By the time Stiles gets out, he's already gone, and Stiles curses when he sees the time on his cell phone. If he doesn't hurry, Derek will get to his house before he does.


	2. Incommensurable

The sterile smell of his room catches him off guard when he crashes through the door, because he's already changed his sheets, and washed the clothes – and when the fuck did he start doing Isaac's laundry, too? - and pretty much scrapped any damn thing he might have that would smell a little too much like he and Isaac have been doing anything but annoying the piss out of each other. It's like walking into a hospital room, almost, and he hates the wrongness of it.

 

It's bullshit.

 

It's not like he's looking _forward_ to a conversation with Scott, something along the lines of _Hey, so you know that werewolf who's maybe tried to kill me a time or two? Turns out I really, really get off on making him come,_ but it's also not like Scott could say much. Jesus Christ, he's dating a girl whose family is in the business of cutting werewolf's _in half_. If it weren't for the fear that runs across Isaac's face any time there's even a hint Derek might find out his little Beta is screwing around without his approval, Stiles might just say to hell with it, and throw a pair of Isaac's dirty boxer briefs in Derek's face to get the message across, loud and clear.

 

But there is the fear, and there is the reality that Derek broke Isaac's arm for the insidious infraction of being a whining teenager, so Stiles will clean, and Stiles will play juggling games, and Stiles will lie to the people he cares about most. Because somewhere between a violent full moon in a jailhouse, and a punch in the face under an oak tree, Isaac becomes worth it.

 

He ducks into the bathroom to brush his teeth and gets distracted making faces in the mirror and imagining Derek as his pack's pimp; it's an image that is as amusing as it is disturbing. He really shouldn't be surprised at anything Derek does these days; he did his best to use Erica to lure Scott to his side, so that he has plans for his other betas is probably par for the course. But it's a sour taste, still, especially when Stiles has long since figured out exactly how Kate was able to infiltrate the Hale household. He's heard his dad talk time and again about the cycle of abuse, and he sticks his head underneath the faucet before he can ponder what that might mean for Isaac.

 

He's scrubbing a towel over his hair when he hears the creak of his window sill, and by the time he gets back to his room, Derek is at his desk, casually rifling through his papers. He has a funny look on his face, which Stiles assumes is because he's removed anything of importance that morning, and replaced it with the most graphic and disturbing hentai fanart he can find. Wolves who snoop deserve to be scarred.

 

“Dude, pretty sure we've discussed this concept of personal boundaries before.”

 

Derek is not, of course, startled, nor does he bother to look remotely ashamed of his creeper ways; he just turns his head enough so that he can see Stiles, and throws out his patented, one eyebrow raised, I'm-sorry-puny-mortal-did-you-think-you-had-something-important-to-add, look.

 

“Interesting hobby.”

 

The door frame is digging into Stiles' spine, but he forces himself not to move from the slouch he's in. It's been months since they've done this, and he's forgotten how Derek makes the room seem unimaginably tiny, like no matter where he turns, there'll be some part of the Alpha there. He hates it, hates the casual ease with which Derek acts like he has a right to do anything he damn well wants.

 

“Well, you know, teenage hormones. What can you do?”

 

Instead of responding, Derek simply changes the subject. Different day, same sourwolf.

 

“What have you found?”

 

“Gee, Derek, no foreplay? I bet your game brings all the girls to the yard. Or the subway station. Have you converted one of the train cars to a little werewolf palace of love?”

 

“ _Stiles_.”

 

“Jesus, fine. I see being Alpha still hasn't improved your sense of humor.” Really, being Alpha has improved nothing about Derek, except maybe his ability to manipulate and control, guilt free. Not that he didn't do it before, but even Stiles had seen how conflicted he was about it. Now, he thinks, Derek _likes_ it, gets off on it. Scott says it has something to do with how Derek was never meant to be Alpha, that his wild mood swings happen because he continually struggles to keep the power from eating him whole, from turning him completely into Peter. Stiles appreciates the effort, he really does, because Derek reminds him of Peter far too much already.

 

For a guy who continually refuses to join Derek's pack, Scott seems strangely invested in making sure Stiles understands where he's coming from, especially on the rare occasions the two packs work together instead of mutually antagonizing each other. Stiles assumes it's because Scott is afraid that one of these days he's actually going to try to carry through with his half dozen or so threats to kill Derek. Which, really, Scott should know better.

 

If Stiles is going to kill someone, he certainly wouldn't give Scott a heads up. Anybody who's watched  _CSI_ knows it's always the best friend who cracks first.

 

He flicks on the computer and plops into his chair, all the air in the cushion escaping in a hissing wheeze. Beside him, Derek stills, his brows drawing together.

 

“Isaac's been in here.”

 

“Yep,” Stiles answers congenially, sliding his thumb across the fingerprint scanner and waiting for his desktop to come up. “Did you think my dad would never find out I had a teenage stalker? It's a lot easier to explain working on chemistry projects than homicidal werewolves.”

 

A truth, a question, and a truth. He realizes months ago that he needs to find a way to work around the werewolves' built in lie detectors, and practices with Scott until they figure out how to lie without lying, to avoid while still answering. He doesn't do it often, but this one he's expecting – the smell of sex he can remove, but Isaac's been here too often for Stiles to completely wipe his scene away.

 

Derek's eyes narrow, but they're focused on the screen, and the document Stiles has opened. “What's this?”

 

“That, my hairy friend, is archaic Japanese. And you are so lucky I found somebody who can translate it.”

 

As quickly as possible, he fills Derek in on what he's found, ways to identify the katsune, ways to track and capture it, ways it can be killed. Fate of the good folk of Beacon Hills notwithstanding, his dad is due home soon, and he's just not in the mood for a game of “hide the werewolf”.

 

When he finishes, Derek straightens from where he's been hovering over his shoulder. “Good. We find it, and we kill it.”

 

“Actually,” Stiles ventures. “We might not have to. Allison said her dad knew some hunters who ran across a katsune that had learned how to live off..um...dead people parts. Maybe if this one knew it had that option...I mean, they're basically people, right? It's probably easier to rob graves than be a serial killer.”

 

Derek is working his way across Stiles' room, picking up various things and putting them right back down again. When he begins leafing through  _Frankenstein_ , Stiles has to resist the lunge at him and jerk it away.

 

“You're basing this off the assumption this thing doesn't enjoy its killing. Do you remember those bodies? You don't kill like that unless you're having fun.”

 

“Look, all I'm saying is that killing might not be our only option.”

 

Derek drops the book on his bedspread. “I'm not taking that chance. It's murdering people. We're taking it out.”

 

“Because your judgment is so damn good? Like with Lydia? And Jackson? And Matt and Danny and Victoria? You'll forgive me for avoiding the blind leap this time.”

 

“It's not your call.”

 

“Hey, guess what? Not your call, either. You don't get to run this show.”

 

It's not really a surprise when he finds himself yanked from the chair and slammed into the wall, Derek crowding into his space, but even so, he finds himself balancing at the edge of a full on freakout. Not because he thinks Derek is actually going to hurt him – he can generally tell the difference between pissed off and needing to assert his wolflihood and when Derek goes truly psycho – but because Derek is taking up room that isn't his and the wrongness is something Stiles feels all the way down his spine.

 

This is  _Isaac_ 's space; it's a truth that comes in a startling flash of awareness. Only Isaac belongs here. Isaac, pressing his face into the crook of his neck and whining, long and low, when Stiles rocks them down into the mattress. Isaac, making wrecked sounds as they kiss, and then sliding his way to Stiles' chest to worry at his mark. Isaac, eyes closed, his head in Stiles' lap while he reads to him.

 

Isaac, dropping to his knees - 

 

Stiles wrenches himself back to the here and now, before his mind disappears down completely inappropriate channels, but his breathing has at least gone back to normal, and the tight flare of panic in his chest recedes.

 

Derek is watching him, a satisfied smirk on his face, no doubt put there by the evidence that he can still cow Stiles with brute strength alone. He leans in next to Stiles' ear and Stiles has to physically restrain himself from kneeing him in the balls to get him  _away_ ; he actually does want to keep his throat intact today.

 

“Five people are dead. I'm not going to let more die just so you and Scott can hold hands and sing Kumbaya with every supernatural creature that wanders through town.” He shoves Stiles against the wall again for good measure and then steps back.

 

“Your father just turned the street corner.” He's halfway out the window before he turns back in. “Find another excuse for him. Isaac's job doesn't involve being your study buddy.”

 

Before Stiles can rebut that it's not  _his_ job to explain the stalking Derek orders his pack to do, he's gone, and Stiles can only stick his head out and scream into the yard.

 

“This is not the definition of teamwork, asshole!”

 

* * * * * * * * * * * *

 

Several hours later, Stiles is sprawled across his bed, chewing a pencil within an inch of its life as he reads through a set of essays on the collective works of William Faulkner –  _A Rose for Emily?_ Really?! He'd like to shove some of these stories under the nose of people who complain about how obscene and macabre his generation is.

 

There's a noise at the window, but before he can even start to panic, Isaac pushes it open and climbs inside.

 

It's the first time he's ever shown up when Stiles' father has been home.

 

“Hey.” Stiles pushes his papers to the side and sits up. “I thought you were --” he makes a circling motion with his finger.

 

“I am. We are. I can't stay.” He sits on the edge of the bed and flips through a few pages of Stiles' textbook. “I still have to write my reading response.”

 

“It's not bad. So what's up?”

 

“I --” Isaac draws his knees up to his chin and wraps his arms around them, resting his cheek there as he turns to regard Stiles. “I just --” he licks his lips. “This afternoon...What I did wasn't n-n-normal, was it? People don't...people don't just do that, do they?” 

 

He hasn't heard Isaac stutter since before he was turned.

 

“Uh...” No, no they do not, at least almost seventeen year olds don't, not outside of porn, but almost seventeen year olds usually don't run around killing people or hunting kanimas and katsune and getting shot at by adults on a semi-regular basis, either. “You're not just people. You're, like, Isaac Lahey, werewolf extraordinaire. Dude, you've practically lived in my backyard for the last three months. Pretty sure none of us meets the definition of normal.” He stops, backs up.

 

“Wait. Did you come here to apologize for blowing me?”

 

The fingers worrying at the fringes of the hole in the knee of Isaac's jeans pick up speed. “Kind of? And for the...for the staring. And not leaving. You didn't...um...you didn't want me there. I don't...I don't always know...sometimes my brain...” He's tugging on his own hair now, watching the wall with determination. “Sometimes I think there's two of me...”

 

Stiles has no idea what the  _fuck_ is going on, except maybe Isaac is starting to have a panic attack, because he begins to rock, back and forth. Stiles wraps his fingers around his wrist and yanks his hand from his hair, half afraid Isaac's working on pulling out a chunk of it. Isaac flinches and then goes still.

 

“Hey --” Stiles scoots closer and knocks his shoulder against Isaac's. “I wanted you there. Trust me.” His voice ratchets higher and squeakier, because just because they're doing it, doesn't mean he's used to _talking_ about it. “I really liked it. A lot. I kind of thought you could tell.”

 

Isaac's face is buried in his knees, but the tips of his ears are pink. His  _yeah?_ is muffled, but comes through.

 

“Yeah.” Stiles jumps off the bed and rummages through the basket of clean laundry, the sudden rise of the mattress enough to make Isaac raise his head and watch him curiously. Stiles finally finds one of Isaac's shirts and holds it out. When Isaac doesn't immediately catch on, Stiles smirks and shakes the shirt.

 

“Come on...you know you hate the way this room smells right now.”

 

The second it clicks, Isaac is across the room, pinning him to the wall and snuffling at his neck. The tension Stiles has unknowingly been carrying with him, since his encounter with Derek, leaks out of him, his jaw unclenching and his body going slack into Isaac's. He literally cannot think of anywhere else he'd rather be right now.

 

He's so fucked, but it's the best kind of fucked ever.

 

“I want to stay.” Isaac's fingers are pressing into his upper arms, and he's pushing as close to him as he can get without starting _that_ , because there's no time, there really isn't. His breath is making moist puffs against Stiles' jawbone; he's doing his best to keep their skin touching. “I want to stay.”

 

“I know...I know.” He slips his fingers underneath the hem of Isaac's t-shirt, just barely touching skin, and then cards his hand through Isaac's hair. “But you already said you can't.”

 

Isaac shudders and nods and then steps back. He pulls his t-shirt over his head and replaces it with the one he takes from Stiles, before balling the dirty one up and shoving it under Stiles' pillow. He's biting his thumbnail and staring down at the bed when he says - 

 

“I'm not supposed to be in your room anymore.”

 

Stiles thanks all that's holy (unholy?) that he risked texting Isaac about that particular conversation. “I thought that was already a given?”

 

Isaac just chews harder on his nail. “Not...explicitly.”

 

Stiles pushes his palm into the coldness that has become his stomach. “Are you gonna listen?”

 

He can  _see_ the fight, the indecision that rolls through Isaac's body, and he's grateful all over again that he didn't let Peter bite him. If Scott's being stupid, Stiles can just walk away, can tell him no. He's pretty sure it's not so easy for the actual werewolves, although Erica seems to buck Derek with regularity.

 

In the end Isaac looks over his shoulder at him and shakes his head. “No.”

 

He breathes deep, feels his belly grow warm again. “Oh. Good. See you at school tomorrow?”

 

Isaac nods and touches Stiles' pillow one more time before heading to the window. He smiles before he climbs out, bright and open for a change. “Bye.”

 

Stiles stacks his books and papers on the nightstand, setting his alarm early enough so that he can finish in the morning.  _Frankenstein_ is the last to go on the pile, and he checks to make sure the bookmark didn't fall out when Derek dropped it earlier. They're almost finished, and he's going to insist on a happier read the next go round, because holy hell, he wants to weep for the stupid monster on a daily basis.

 

He switches out his light and falls asleep on a bed that still doesn't smell quite right, but is miles closer than when he walked in this afternoon.

**Notes for the Chapter:**

> So, the next portion of this story is pretty heavy on the serious and angsty side, because everything comes to a head. I'm debating doing a short oneshot in between, something focusing on a lighter moment between Isaac and Stiles (I know it's a surprise, but they do have them!) Thoughts?

**Works inspired by this one:**

  * [Factoring Out Binomials (The B Side)](https://archiveofourown.org/works/461434) by [GoddessofBirth](https://archiveofourown.org/users/GoddessofBirth/pseuds/GoddessofBirth)




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